Phase transition in salt-free catanionic surfactant mixtures induced by temperature
Aggregate transitions in salt-free catanionic surfactant mixtures of tetradecyltrimethylammonium hydroxide (TTAOH)/fatty acid were investigated as a function of surfactant concentration and temperature. Lauric acid (LA), myristic acid (MA), and palmitic acid (PA) were chosen for the current study. T...
| Veröffentlicht in: | Langmuir : the ACS journal of surfaces and colloids. - 1992. - 26(2010), 1 vom: 05. Jan., Seite 34-40 |
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| Weitere Verfasser: | , , , , , , , , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2010
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| Zugriff auf das übergeordnete Werk: | Langmuir : the ACS journal of surfaces and colloids |
| Schlagworte: | Journal Article |
| Zusammenfassung: | Aggregate transitions in salt-free catanionic surfactant mixtures of tetradecyltrimethylammonium hydroxide (TTAOH)/fatty acid were investigated as a function of surfactant concentration and temperature. Lauric acid (LA), myristic acid (MA), and palmitic acid (PA) were chosen for the current study. The TTAOH/LA mixture exhibited rich phase behavior at room temperature. With increasing total surfactant concentration (c(T)), a bluish vesicular (L(alphav)) phase, an isotropic micellar (L(1)) phase, and a birefringent lamellar (L(alpha)) phase were observed. Between the L(alphav) phase and the L(1) phase, a narrow L(alpha)'/L(1) two-phase region was determined. With increasing temperature, a transition from the L(alpha) phase to the L(1) phase was induced at higher c(T) whereas at lower c(T) an opposite transition from the L(1) phase to the L(alphav) phase was noticed. Thus surprisingly, we observed bilayer-to-micelle and micelle-to-bilayer transitions in the same catanionic surfactant system, both induced by the temperature increase. Replacing LA by MA and PA caused a continuous increase in the average Krafft point of the mixture. The L(alphav)-phase region and phase-separated region become larger. Moreover, a single L(1)-phase region was absent within the investigated temperature range |
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| Beschreibung: | Date Completed 02.03.2010 Date Revised 29.12.2009 published: Print Citation Status PubMed-not-MEDLINE |
| ISSN: | 1520-5827 |
| DOI: | 10.1021/la902069w |